ltelearningfandomcom-20200213-history
LteExtendedCourseNotes
FDMA/TDMA 2G: GSM -> 13 Kbps MSC --- GMSC (GMSK - moudlation - 1 bit per symbol) 2.5 GPRS -> 171,2 Kbps SGSN --- GGSN ( (GMSK) 2.75 G: EDGE (we could miliply throuput GPRS by thre ) 171,2 x 3) ( 8-PSK modulation, 3bit for symbol) 3G : WCDMA - codes (Band is 5Mhz) (but we are using 3,85 - to protect the interfernece from other systems) R99 - first implementeation 3G UMTS - > 384 Kbps/ R4: MSC splitted in two parts - > MSS (Control Plane - signalig) and MGW(Media Gateway) - reposible for UPlane We achived the throuput 2Mbps (by reducing latency by splitting) R5/R6 - Focused on data domain GGSN | SGSN | RNC | NB ENB can now make retranmission (by adding mechanism of retransmission on MAC) - previously it was only RNC (that used ACK (slower)) Enb is smarter - talks to MAC/PHY - H-ARQ - Hybrid automatic repeat on rewqust - Fast retransimmision Slow retransmission is in RNC (as layer) - this is ARQ - slow retransmission HOw HARQ and ARQ works together , if HARQ retransmision is too much, ARQ is involved If maximum of retransimision is reached - HARQ limits 1..16 in DL 1..7 in UL Maximum number of retransmission is set in Enb R7: Two steps 1 step: IN data domain we splitted SGSN will be reponsobiel for control plane, and GGSN for UP GGSN | - direct tunell 2 step: we will all functionality RNC into ENB. Enb has now functionality of RNC inside GGSN | ENB Layer that Enb speak now: RLC MAC PHY (enb is smarter Eeasier to move to LTE (with second step) because they don't have to buy new hardware R8: Software upgrade Enb we add I-HSPA adapter to Enb and than ENB will work as ENB+RNC functionality SNGS - after upgrade becomes MME SGSN - after upgraed becomes SAE-GW SAE-GW = S-GW + P-GW (Harderw FLexi NG) MME || eNB R8 is 3.9G (becuse of throughput) 150Mbps TO call 4G we must fulfill condiition - we have to reach 1Gbps - we will do int in LTE-Advanced (release R10) HSS ..... MME PCRF UE --- ENB S-GW P-GW ------ PDN MME - Mobilit Management Entity Control ENB - signaling point Reads NAS message - Non Access Statrum - Directly UE-MME - Enb e.g. Attach , Security Enb is not responsible to make an attach other example of NAS - Tracking Area Update - Cell cpecific Tracking Area is orginization of cells - we need UE to locate it quicly - we page UE in Tracking Area If you are Idle mode I have to page to find you. If you in active mode I know Tracking Area should too small - to big traffic area updates flow too big - to much paging TAL- tracking area list - UE is keeping tracking alreay list TAL - TA1,TA2,TA3 ( if moving in the same TAL - ue does not inform MME) TAL2 - If I what to page you I page on last Tracking Area, if not found I page whole Tracking area list teorically i page in whole PLNM (operators disable it often) S-GW - functionality: Packet routing and forwarding to P-GW Lowfull interception LIG - Lawfull Intercepetions Gateway - S1 - Handovers(Feature - operators have to pay ) One S-Gw can be conneted to more than one P-Gw depending on operator configuration S-GW Hardware - Flexi NS (FLexi MME) - Flexi NG (S-GW, P-GW) (APN - Access Point Name) - PDN connection UE - can have more than IP because it can be connected to different APN Operators can devide build APN - P-GW - functionality: Ip address allocation Charging - (can be based on time, volume, event(sms,mms) online charging - as long as you commnitate, I will charge you e.g. every second offline charging - CDR - Chargin Data Record to billing center is sent after communication Lawfull Interception - LIG can be connected to SGW and PGW Ue is connected to only one S-GW Ue can be connect to multiple P-GW MME can support (theoretically) enb 10M ue In IDLE mode UE In CONNECTED mode UE - 840(UE) - PCRF - Policy and Charging Rule Function QoS coordination - Quality of Service coordination PCC - Policy and charging control AF(Application function) | PCRF | PCRF Policy and Charging enforcement PGW OCF (Online Charging function) OFCF(Offline charging function) QCI - Quality of service class Id QCI1 ...QCI9 QCI1 - most important, - for voice over IP QCI5 - IMS Signalling QCI1..QCI4 - Guaranted bitrate QCI5..QCI9 - Non guarated bitrate QCI of Bearer, what is Bearer RB - Radio Bearer - like a tunnel of specifc quality of service LTE - - Enb - S-GW P-GW < external Bearer> PDN --------------------------- EPS Bearer -------------------------- (entire path above) EPS - EPC + SAE = eUTRAN + SAE Deidcated Bearer is alwasy linked to default bearer If incactivity timer expires (in 30 seconds) RB is deleted, S1-beare is delted, but s5/s8 is NOT deleted 840 UE * 5 bearers ? ARP - Allocation retention priority ( can allocate some bearer to one ue (and if it is full) it can discrard someone others bearer) Capability - Y - can preempt other Vulnerabity -N - no one cannot prement me IMS - Ip Multimedia Subsystem HLR - cannot use in LTE network (as single) HSS - Home Subscribe Service = IMS + HLR MSS - MSC server CS - Circuit Switch Two technologies to implement voice communication CS Fallback - must brak interned download to start talking in 3G Voice over IP -- posible to voice and talk - QCI1 and QCI9 IMS SC DOmain Packet Domain Handover vs Redirect LTE | 3G/2G Connected -> Connected (HO) Voip | | | SRVCC - Service Radio Voice Call Continue (RL40 feature) Idle ------ > Idle ( Reselection - functionality of UE (Not ENB) ) Conneted --- Idle ( Redirect ) Idle ------ > Connected ( CS Fallback) eNB S1-MME S1-App SCTP IP L1/L2 Application Transport - >UDP/TCP/SCTP Advantage of SCTP is: Multihoming - you can have more than one IP address Means, you have one link, but you can have more than one IP addresss None! One ENB can be connected to more than one MME ( by link S1-Flex) reasons for multiple MME to one UE - redunandcy load balancing faster handover enb-sharing - two operators may share one enb S-GW - S1-U - Protocol stack GTP - U UPD IP L1/L2 X-2 Protocol stack X2AP SCTP IP L1/L2 GTP-U UPD IP L1/L2 Between two MME - Protcol stack GTP-C ----- UDP IP L1/L2 MME --> HSS (S6 Interface) S6aAP DIAMATER - (Previously it was RADIUS but it was smaller) SCTP IP L2/L1 SAE Gateway - combination of P-Gateway and S-Gateway Plug and Plau Auto connectiona and autoconfiguration SCF - Site configuration file enb Hardware ID In FDD we have ENTIRE frame for downlink and ohter for uplink In FDD we have part of the frame for uplink and some for downlink Special subframe - (In TDD) - from the ENB to the UE , guards the when DL will Timing Advance - when to start eminting (UE) so the ENB will receive. Enb calculates RACH request Coverage is related to the power (UE) that it has to consume Assumption - TDD and FDD have the same througput TDD advantage - if there is no available spectrum - you can use one frequency - better flexibility - there is no waste in UL (when UE is not transmitting) Why we are not using OFDMA in uplink ? because of Peak to power ration PAPR Peak to avarage power ration is too HIGH SC-FDMA has much butter (lower) PAPR We are not using SC-FDMA for the Dowlink because it difficutl to decode. UE will not be able to do it. But Enb is OK with that (because of Cyclic prefix) X2 link can be implemented as X2 - star - all enb are connected to SEG (security gateway - router with IPSEC functionality) X2 - mesh - connect all the enb together X2 mesh is recommended because it invlove less number of links eNB can be connected to onlly S-GW MME provides addres for SGW to enb. MME chooses S-GW depend int on Tracking area code MME chooses p_GW dpend on APN --------------------------------- END OF DAY ONE -------------------------------- Why we need IMS in lte - to translate from packet to CS (circuit switch) - make the interconnection between the PS Domain and CS domain (IMS - IP Multimedia Subsystem) P-GW - IP address allocation (many IP's depending on APNs) The number of default bearers indicate how many IP address are already allocated - charging (offline and online) UE - eNB protocol stack RRC - control plane PDCP -- user plane RLC MAC PHY Applcation - FTP Transport - TCP Network - IP Layer2 - PDCP.RLC.MAC Layer1 - PHY RLC/MAC/PHY are only in air interface because it is not reliable so we have to indotruce new one for Security/retransmission and ... ---------------------------------------------- PDCP - Packet Data Convergence Protocol Ciphering + Integrity IP Header compression (not for whloe packet, only header) (ip header ROHC or ZUC (RL50)) function:Ciphering (no one can read) function:Integrity (no one can write (modify)) digression (FGI - Feature Group ID - sequecne RLC - Radio Link Controll SLow retransmission (ARQ) ARQ - UM or AM or TM , Unacknlowedg mode, Acknowledge mode, Transparanet Mode(no segmentation) I choose ARQ depended on QCI AM - qci (for not real time application) (kind of TCP) QCI 5,6,7,8 UM - qci (for real time application) (kind of UPD) QCI 1,2,3,4 Todays mobile does not support QCI1 so they dont support UM Transparment mode - it goes directly to the MAC Layer (does not see RLC) CCCH - Common Control Channel (is configured in TM) function: Segmentation SRVCC - SIngle radio voice call continuation - (some kind of handover to 3g/2g architecture) witheout discconection - handover (mobile does not go to IDLE mode) In UM mode if HARQ and ARQ cannot get correct message than we just drop the packet If RLC in AM cannot get message it goes to TCP layer(upper layer) and whole message is requested MAC - main function fucntion: H-ARQ function: scheaduling(periodicity of scheaduling 1ms) scheaduling of resource blocks max 7 symbols per 0.5ms can be transmitted (15,khz) 66,67 microsecon Resource block is compoesed of 12 subcarriers In 20 MHZ i have 100 hunderd resource blocks (12 hunderd subcarriers) FOr scheduling the periodicty is 1ms (1TTI), AT least I will allocate 2 resource blocks (in time, not frequency) Transport blocks - 2 resource block Size of Transport block is variable (depend how much data to be transmited, on modulation and coding) E.g. 64 QAM , 100 RB TBS = 75376 bits (TBS - transport block size) Transport size depends on - how many user priority on user depends on QCI and signaling PHY - functionality modulation coding OFDMA/SC-FDMA (diff: how the symbols are spread across frequency layers) RRC - Radio Resource Controll func:Admission controll func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted Trusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted Trusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted Trusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted Trusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted Trusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted Trusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted Trusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted Trusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted Trusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted Trusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted Trusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted Trusted func:Handove controll func:Bearer manaement func:Security func:Paging func:System info broadcast INterworking with 3gpp access NOn 3gpp network - CMDA 2000, Wimax, WIFI ( connecting by P-GW) Two types of non-3gpp network Untrusted - networks that use other technik for authenitcation than AKA (e.g. Trusted - networks the using the same mechanism of authentitcation that 3gpp uses (the use AKA - Athentication Key Agreement) CK - Cyphring Key IK - Integrity Key Kasme - Key access security MME KnasINT - Key non access stratum INtegrity, Knas ENC - Key non access stratum encyrption Kenb - Key enb KRRCin KRRCenc KUplaneEnc ePDN - AAA - Authorinzation .. Authentication and Acounting RRM - Radio Resource Management func:Handover control (on layer RRC) HO control Network COntroleld (enb take decission) Ue assisted (Ue send measurment) Late Path switch (EPC is involved, only after handover is successful) Hard HO (break before make) UE assisted ( ue will send measurement ) - RSRP - Refenrece SIgnal Refence Power if RSPR signal will be below threshlod (Listened by UE) - trigger the measurement A2 A2 event trigger the measuremnt A1 event stop the measurment A3 offset - diff between serving and neightbour when A3 is 3db (2 times better-be configure to different value) A3 event, - this will trigger the report (measurement) A3 time to trigger - to avoid PING PONG Handover (time to wait when start reporting) A5 event - (serving is some hardcoded trheshold, neighbour is in some hardcoded trheshold) 1. Threshold 1 - UE will listen to Intrafrequency In LTE frequency is requse 1 - it means only frequency on the entire network (NO frequency planning) 2. Threshold 2 - Interfrequency (can also use RSRQ) 3. Threshold 2 - UTRAN 4 3Threshold 2 - GERAN 5. THreshold 2 - CMDA 2000 Recommanded - THreshold 1 to greated Measurement gaps - time when I disconnect from the serving and swithc my transmission to listen to the neighbour (needed for Threshold 2 ) RSRQ - Reference Singal Resource Quality (second criteria to make handover - or start listen A4 event - when the neighbour is better than the threshold (for Load balancing) when enb is 80% loaded and want this UE to jump to less loaded cell L3 - NAS RRC L2 PDCP RLC MAC L1 PHY RRM func: MIMO (on layer between L1 and L2) differrent type of MIMO 1 type Transmit diversity (Txdv) - two antena, sending same infomration through two antenass (same codeword) (improves SINR singal to inteference noise ratio) gain of 3db (2x power) 2 type Spatial mutiplexing ( ) - difeerent codewords on two antenass - Throuput is increased (up to 150 Mbit) - coverage is spatial multipelxing - differnt type of mode: . open loop (static open loop) . closed loop - feedback is PMI . (recomeneded - more flexible) Dynamic open loop - swtich between tx diversity and spatial multiplexing - depending on channel condition (good condigiton, spaitial, if bad - transmit diversity) parameter that reflect channel condition - CQI - channel quality indicatior (1..15) - can configure threshold - based on that , enb will choose wheter to use spatial, or diversity differnce between open and closed loop - open loop withouht feedback Enb will receive on two antens - with spatial diversity - singal from uE comes on thow paths Polarization - one of way to distinguish two paths closed loop (with feedback) - used PMI to get feedback PMI - Precoding Matrix indicator H11 H12 H21 H22 Multi user mimo - MU-MIMO Multiplex serveral UEs on the same Resource Block - we are increasing capacity CQI - Ue sends it dependint it on SINR - Ue will know SINR from RSRQ, ue will know RSRQ from RSRP RSRP = N x RSRP / RSSI, N - number fo resource blocks RSSI - Received singal strenght indicator - power for the whole subcarirers (power + noise + interference) RSRP - only the power of refernece signal Beamforming - advanced technique for mimo - two kinds (RL15 - one codeword ) RL25 - two codewords (only in TDD implemented) (FDD estimation for channel quality is differen, in TDD quality for DL is almost the same for UL because we use the same frequency) TO boost the power by for specific UE (but creates problems for UE that is located behind this one) RRM func: Admission control (RRC - L3) We control: Max nr of RRC connected, (we have SRB already allocated, SRB0,SRB1, SRB2) FDD: 840 in 20Mhz, 420 10 Mhz, TDD: 400 UE in 20 Mhz, 200 Ue in 10 Mhz Max nr of Active UE (we have DRB) Max number of bearer 4200 ( in 20 Mhz: FDD ), TDD: (2000 bearers, (20Mhz) (4200 - assuming that all UE have 5 beaers each) ARP - Allocation Retention Priority - capability and vulnerability of the baerers RRM func: AMC: Adaptive modulation and coding Choosing best modulation and coding depending on radio condition Modullation - depending on channel condition (from CQI) In DL is based on CQI, i UL it is based on BLER (Block Error Rate/Ration) UL is based BLER = number of Erronous TB from HARQ(because it is mandatory, not ARQ becsue if we confgure UM there will be no ARQ) / TOtal transmitted TB Feature in AMC: OLQC - Outer link quality control - (correct QCI wrongly send by UE) - use the corrected CQI not the reported CQI if feature is enabled , it will NEVER used reported CQI, always correct How it will correct : ? Using the BLER ILQC : Inner Link Quality Controll - use repored CQI without correction, ATB : Adaptive Transmission Bandwidth Power headeroom - how much remiaing power before we reach maximum (UE ), ue will periodically report its headroom. how te reduce of power - reduce MCS - > till you reach MCS minimum (MCS - modulation condig scheme) reduce Throughput - reduce the numer of resource block DRX in idle mode (Paginc cycle) - not a feautre - standard DRX in connected mode We dont want UE to transmit high power (becaue it crates interference) IMS ( L1/L2 works on ) RRM func:Power Control (layer L1/L2) power control in DL, UL in DL is semi - static in the beginning I will confugire what will be the power , 8,20,40,60,80 W (RL40) in UL open loop Power control - without feedback closed loop Power control - with feedback from eNB for open loop how UE knows the power it should tramist - it knows from Path Loss from RSRP but when we start and dont have the measuement data - we know it from Sib - initial Tx power UE says "excuse me" to the eNB - called Power Ramping - uppering power by steps until eNB will hear for closed loop - enb ask the ue to increas or decreas the power from SINR and RSSI PCC = Policy and Charging Control we will find in this QCI ARP MBR - maximum bitrate (only for GBR) (for every single bearer) AMBR - aggreateion max bitrate (NON-GBR) (from all NON-GRBR) TFT - Traffic flow Template ( to differnate when we want to e.g. use voip and sufr internet at the same time) Scheaduling CSI - Candidate Set 1 UE should not be in measurement gap UE should be synchronized with eNB (in connected state) UE has data in his buffer, ue says it by BSR - Buffer status report lets say we have 90 ue that fulfill CSI lets select CSI 2 CSI 2 select from CSI 1 the maximum of number of ue that can be allocated (for 20 mhz it is 20 ) choosed 20 from 90 prioritize by: HARQ SRB DRB Roaming architecutre - two types of roaming - local breakout, remote breakout - depend on technology (remote - means I have to connect to my home P-GW) LTE reuse network Ue is distinguishng the cell by using PCI - Physical Cell Id , like the scrambled code in 3G composed - pci sector and pci group 3x PCI group + PCI sector PCI group is (0,1..167) PCI secotr (0,1,2) PCI 3x165 +2 (all the cells should belong to the same group) Two neigbour cells should have different sector assigned RL30 - 6 cells per eNB in FDD two neighbour cells does not have problem with to neigbhour cells having the same sector ID but ther is problem with TDD because they have to be synchronized (by the GPS), in FDD they are not synchronized so ther is no problem PCI is not unique in PLMN How can we identify CELLs inside PLMN in unique way ? Uwe are using eUTRAN CELL ID (28 bits) 20 bits - bts id, 8 bits - cell id BTS ID 0...1048575 2to20 power eUTRAN Cell ID = 256 x BTS ID + cell ID CGI - Cell Group ID PLMN ( MCC MNC) BTS ID, Cell ID = unique across the word (CGI: Cell Global ID) - used for ANR (Autmatic neigbour resoluation) we must avoid PCI mod 3 for adjacent cells in FDD no problem because they are no syncronized in TDD we have problem because they are synchronized by GPS ------------------------------ DAY 3 ----------------------------- Protocol stack between UE and eNB RRC L3 PDCP L2 RLC L2 MAC L2 PHY L1 This protocol stack is only in the air interface, not in cable. PDCP funcs: Cyphering ,integrity, IP header compression - Robust overhead compression, RLC funcs: Slow retransmission, Modes UM,AM,TM (depending on the QCI) qci5- IMS sygnalling - to converto to voip to circuit switched funcs: Segmentation and contatenation MAC: HARQ, Scheaduling, we scheadule resoruce block - min Resource block (in time domain), periodiity of scheaduling (1ms) in 1 ms can be schaduled 100 (standard), PHY: fucn: OFDMA and SC-DMA RRC: all signaling funcitonality, bearer management, beare security. RRM: funcionality of RRC (anwsers to question what enb can do in the manner for air interface) func: handover controll (decision of enb) a2 trigger the measurement in LTE HO: hard handover : break before make func: MIMO (L1/L2) tx diversity - increase coverage by 3db spatial multipexing - different codewords - improve throughput func: Admission controll (layer RRC /L3) RRC conencted has SRB Active Ue has DRB Max number of bearer per UE is 8 Max number of berare 4200 (each ue has 5 beaer) func:Power control (layer L1/L2) Max power in enb (80Watt -RL40) func: AMC - Adaptive modulation and coding in DL enb will know modulation and coding - based on CQI, in the uplink by the BLER In LTE there is no need for frequency planning --- END OF RECAP FROM PREVIOUS DAY --- IMSI - identifier of the ue (is hardcoded in SIM) S-TMSI - Short TMSI M-TMIS - allocated by MME RRC - COnnected S1 - COnnected RRC Connected + S1 Connected = ECM COnnected AFter Attach - we have Attach complete Ue goes to state EMM registerd (EMM EPS Mobility Management) ECM Idle - (go to that state after inactivy timer (defuault 30:second) After attach the defult bearer is created - (composed of Radio bearer, s1-bearer, and s5-s8 bearer) in s5-s8 bearer exit as long as you are registered, but after inactivity timer RB and s1- bearer is removed EMM registered -> EMM deregisterd (switch off you phone) INside MME there is timer T3412 - if we not got tracking area timer until this time we (54 minutes : default), this treat UE as dead Inside the UE we have periodically Tracking Update. Every 54 minut UE sends Periodic Tracking area udpate. T3412 is set in MME. Ue will know it from system information DUPLEX - multipe users on the same resource Challenge of the AIR interface 1. Problem : adjacent carrier interface - to overcome - rectangle Pulse (to move from time to frequency domain - Fourier transform) subcurier interference - to avoid we use ortogonality, means that next one adjacent subciarrier (ACI - adjacent carrier interference) In LTE - 1/15KHZ = 66,67 microsecond - Nyquist criteria - 66,67 is the lenght of resoruce in time 2. Intersymbol interference - overcome by inserting Cyclic Prefix ("guard period") How long it should be - related to the delay spread of the channle ( the longest path - the direct path) if the Dealy spread is 1,4km = Normal CP (7 symbol per 1.5 milisecond) if 5 km , = Extend CP (6 symbols per 1.5 milisecond) Cyclic Prefix - last part of symbol is copied The UE will know when the symbol starts by using the correlation between the CP and the last part of symbol (should be the same) (fft - fast furier transformation) Nfft > Nsc (subcarriers) - > Sampling In 5Hz - number of sucarriers (2 to power of...) 20 Mhz - > 1200 subcarriers 10 Mhz - > 600 subcarriers 5 Mhz - 300 subcarriers 5Mhz - 300 Sc -> 512 Fs (frequcney of sampling) = 512 x 15 Khz = 7,68 Mhz = 2 x 3,84 Mhz (LTE and WCDMA has the same clock time) 15 Khz - WCDMA and LTE can have easier handover, and you can have the same hardware for both technology (it was choosen for smooth evloution from CDMA to LTE) Ts = 1 / 2048x15000 = Time of sampling in LTE for the normal CP Ts = 144Ts = 4,7 micro sec Extended CP Ts = 512Ts = 16,7 micro sec symbol duration = 2048 Ts = 1/1500 = 66,67 micro sec 3. Problem - Inter carrier interference - ICI Loosing ortogonality between adjacent subcarriers due to dopller effect How we can avoid it - by adding referenc signal the distance between two subcarriers must be 6 subcarriers PCI mod 6 = is the position of reference signal - give you the sift of reference signal paul.wad.homepage.dk/LTE/lte_resource_grid.html Speed of light 1 km -> 3,33 micro second Transport channel processing Turbo coding - first send systmatic bit - if I get NACK i send Redundancy version 1 , RV2 and RV3 At max I have 8-HARQ Process - means i have 8 cyclic buffer Rate matching RLC logical channels MAC transport channels PHY physical channels Logical channel - different type of functionality - logical organization of functionality e.g Boradcasting - BCCH Paging PCCH BCCH PCCH DTCH - Dedicated traffic chanel DCCH - Dedicateh control channle CCCH _ Common control channle MCCH - MTCH MAC channels -have the same characterisic regarding transmmision are put together (e.g. they all use the same modulation, type of coding) Having the same characteristic regarding transmission (modulation, delay, coding etc.) DL-SCH (Downlink channels) Physical channel - palce in the grid - physcial resoruces PBCH - Physical Broadcast chanell PDCCH - Physcial downlink control channel - this channel is not mapped to transport or logical channel, it is PURE physical channel (size is variable) can be 1,2,3,4(1,4 Mhz) - depending on cell load PCFICH - Physical Controll format indicator channel - says how wide is PDCCH PDDCH adaptation - number of symbol PDCCH will be dynamically changed based on the cell load PCFICH location is to be found by some formula - PURE physical channel PHICH - Physical H-ARQ indicator channel - Downlink channel - PURE Downlink channel MIB - downlink bandwitdh - (5/10/15/20 Mhz) system frame number (SFN) 0..1023 - we need the SFN for the paging , we need to tell UE when to wake up Ng factor - PHICH configuration (Number of PHICH resources = x N(DL) RB / 8 1 PHICH resources = 12 RE, Scheadule 8 UEs Resource Element Group is 4 useful resource element - elements without referece sygnals 10 Mhz BW = 600 subcariers = 50 PRB 20 Mhz = 1200 subcariers 1. per resource block 3 element / Rb 200 + 200 + 300 - 9 - 4 = 687 REG 1/6 * 100/ 8 = 2.083 3 * AGL - Aggregation level AGL1 =1 CCE, = 9 REG, one CCE - Channle control element AGL2 = 2 CCE = 2 x 9 REG .. AGL4 = 4 CCE .. AGL8 = 8 CCE ... 687 REG = 76 CCE ---------------------------------------------------- END OF DAY 3 --------------------------------------------- ACI - adjacent carrier interference (solution: ortogonality between subcarriers) - by implementing Nyqist criteria. Choose 15khz to be ISI - inter symbol interference - solution: using cyclic prefix. To kind of CP: Normal and Extended of cyclic (normal for max 1.4 km), (extended 5.0 km) for NOmal : first CP is not the same size as othes (in frame), (reason: to match the clock) for Extended : all prefixes are the same Ts = 1 / 2068 x 15000 Inter carrier interfercenc - doppler effect - solution: using reference signal location of refernece signal in frequency domain depends on PCI mod 6 for PCI=20 first (20 mod 6 = 2 ) so the first will be on 2 position (0-based) Logical Channels (RLC -- MAC) Transport Channels (MAC -- PHY) Physical channels (BELOW PHY) Turbo coding - xbits -> turobocoding > 3x bits (systematic bits, first parity bits, second parity bits) Circular buffer Logical channel - functionality (boradcast, paging, multicast, dedicated traffic channel) BCCH PCCH DTCH DCCH CCCH MCCH MTCH ------------------ END OF RECAP -------------------- PBCH - contains information in 1920 bits - QPSK (2 bits per symbol) - 960 symbols (4 frames) 1 frame 240 symbol (4 symbols in time, 72 subcarriers) 2 frame 240 symbol 3 frame 240 symbol 4 frame 240 symbol MIB is 4 * 72 = 288 (48 is missing ? - it is consumed by reference signals) PBCH is in the middle of subcarriers (regardls of freq it has the same size) DC carrier - direct carrier - empty subcarrier - it is for UE to know the middle of band DC (Dirrect Carrier) (it emmit silence - not transmitting anything) We are only transmitting PBCH on first antenna UE finds about nubmer or antenas from the CRC for PBCH - these CRC are 'hardcoded' (widely known) so the ue can match CRC with the signal it will know what will match for it and thus find out the number of antennas SFN - system frame number 0..1024 (10 bits) it is forwared only 8 bits Ue know the 2 remaining bits, from the number of rame in PBCH UE will wake up every 3 hours from IDLE mode to read to MIB If in this time will change something meaningfull, UE will be paged to read the MIB again PBCH - is first subframe and second slot Transport channels BCH --- > PBCH DL-SCH ---- > PDSCH (Physical Downlink shared channel) (Data, SIB, Paging, RACH response) RACH -Random Access Channel) (The minimum size of allocation block is Transport block) PDCCH - Physcial Downlink Control Channel Before we can read PDSCH: (we have to get info from PDCCH physical downlink control channel) PDCCH - every PDSCH <----- PDCCH(1,2,3,4) <---- PCFICH 2bits (after coding 32bits , with QPSK requires 16 RE) position of PCFICH is known from PCI PCFICH position depend on PCI (forumulat to calculate) Resource elemnent group - 4 Resource element - usefull Resource element ( without reference signal) channel to send NACK and ACK - (HARQ) PHICH - Physical Harq indicator channel - PHICH resoruce element usage depends on parameter called Ng (In MIB) 1 PHICH Resources consume 12 resource elment = 3 element group = we can scheadule 8 EUs 20 MHz, Ng = 0.5 NR of PDCCH symbols = 2 2x2 MIMO How much PDCCH I have ? Aggregation level 1 = 1CCE - 9REG AG2 = 2 CCE AG4 = 4 CCE AG8 = 8 CCE How the ue knows what is the aggregation level Active 'state' has DRB Prach - alwasy 6 Resource block First signal the UE will detect after swich on will be PSS (Primary Sychronisation Signal) Send in the middle of the band - We have DC (silence) From PSS Ue will know PCI sector, and can Time and Frequency sychrnoziation PSS is writting in last part of first subframe, written on 62 subcarriers , and in the half of the frame MIB(blue- PBCH) (PSS use Zadoff Chu) in subrame number 5 - the rest of the PSS TIme and Freq sync means UE can now read one symbol (is able to /decode) SSS - from SSS ue will know PCI group (before) SSS will allow UE to be frame synchronized (means able to read the frame (10 ms)) SSS1 and SSS2 have defferent Zadoff Chu so UE know begin of the frame or the middle In TDD the SSS and PSS are not close to each other inside frame Ue can detect whether TDD/FDD from the distance of SSS and PSS How the Ue will know if it normal or extended Cyclic Prefix ? - distance between PSS's. In Normal 70 symbols in 60 in Extded Ue no will to know Reference sygnal from antenna 1 - RS - reference symbols after referency sybmol UE can read MIB MIB - (on channel PBCH) we need to read PCFICH we need to read PDDCCH Now I can read SIB from PDSCH PDSCH (contains SIB, Paging, Data of the UE, RACH response ) from SIB1 I can now periodicity of other SIBS FDD - SIBs 12 TDD - SIBs 8 Zadoff CHu sequence main characterisitcs: amplitude is always one - avoid High PAPR 2 zc seque and correlatte them , it will be zero - they are orotogonall if if i take sequence and cycle shift i can generated ortgonal sequence (also ZadoffChu) PSS, and SSS(0,1) are ZC sequences RACH SI - RNTI (SYstem INformation RNTI) for reading SIB - not unique P - RNTI (for reading paging) - not unique - C - RNTI (for data ) - CRNTI not idle mode, eNB - assignes CRNTI RA - RNTI (fo reading RACH response) caluclated - by eBN and UE, based on the posision of Ue when sending my RACH TO read system information Ue uses SI-RNTI Rach procuder - PRACH (6 symbol block) Ue sends Rach request (msg1) Ue sends preambule in Rach Ue (64-different preamble) - in sib2 enb sends root sequence and cyclic shift , Ue will be able to generate all 64 preambles number of root sequence, and cycle shift depends on cell range Ue chooses 1 preable randomly when sending RACH Ue starts Window TImer (Ue starts with power level set in SIb, than power ramping if power is too low) Rach reponse - temporary C-RNTI, ULGrant + TA(timing advance) (msg2) (in PDSCH) msg3 RRC Connection Request SRB (RRC Connection reuqest - channel PUSCH , establising SRB0) (Ue sending S-TMSI in it) msg4 RRC Connection Setup enb will try to decode S-TMSI1 and S-TMS2 (if one of them has bigger power) Contension Resolution (Connection Reject is sent to the UE that cannot be (setuped), might be the same if ther are the same power and enb cannot decode (interference) Connection Reject and Rach reject are NOT specific message (they are generated from timer) In handover theris no Contention resolution, there is Contetion Free. In handover the preabmle is allocated , not choosing randomly. Root sequence Cycle shifit PRACH Planning composed by 1 ms CyclicPrefix, Preamble and GuardTimer Preabmle 800 microsecond lenght 839 ZC dequence PRACH Format 1/ 2 RACH density - how many RACH per frame (described by prachConfIndex) (table) by choosing prachConfigurationIndex RACH offset - where to put the RACH (in the manner of frequency) RACH offset = NumberOfResourceBlockOfPUCCH/2 - in the bottom RACH offset = NumberOfResourceBlosck -6 - NumberOfResourceBlockOfPUCCH/2 (parameter inside bts site manager) How to generate 64 preables ? In RACH , 1,25 Khz of size of subcarriers ------------------- END OF DAY 4 WHen Ue switch on Ue will find carrier in the middle (DC carrier) Ue finds PSS - time and frequency sychronized , find PCI sector (now can read 15khz Ue find SSS - will be frame sychronized (10 ms, ) PCI group will know PCI will know TDD and FDD - by distance between PSS and SSS will know Normal CP or Extended CP will read reference signal (estimate channel) will get MIB (on PBCH) - in MIB - bandwith, SFN (8bits- are only forwarding) in MIB - Ng - will know the number of group on PCICH in MIB - Mask - will know how antenna will read SIB - will find in PDSCH - but before PDSCH - must read PDCCH - before PCFICH wich key to decode PDCCH - RA-RNTI and SI-RNTI form SIB1 will know the periodicty of other SIBS Next Ue does RACH - on PRACH channel Ue sends preamble - ue know preamble randomly from 64 (know 64 from Root Sequence and Cyclic SHift (cell range)) Root Seq and Cyclic SHift is to be found in Sib2 If Ue does not have sufficient power , use POwer ramping Initial power is in SIb2 Enb will reponse RACH response on PDSCH channel IN rach response - is Uplink Grant - where to find PUSCH (CCCH is configured in Transparent Mode) TO decode PDSCH(Rach response) Ue must use RA-RNTI Ue answers RRC connection request enb says RRC connection setup Contention resolution - procedure Ue says RCC COnnection Setup Complete - SRB1 is established PRACH planning: Preable Format 0 on Format 1 - depending on cell range Rach density - who many Rach I need in time (Preamble configuration Index) (How many Rach in time) Rach in every frame , or in even frame or other (there is table for it) Where RACH in requency ( RACH must be adjacent to the PUCCH -bottom or top) - PRACH Freq offset (these below are parameters in BTS site Manager) offset = NumberOfResourceBlockOfPUCCH / 2 (if to put in bottom) (low border) offset = NumberOfResourceBlockOfPUCCH - 6 (number of PRACH RB) - NumberOfPUcchRB / 2/ Pramble is ZadoffChuSequence Rach has smaller subcarrier width (1,25 Khz) why do we need below - to generate preambles (they are known from table - but they depend on cell size) Ncs - cycle shift Root sequence - << Preamble generation - slide not in course material but in some file called 03_RA41213EN40GLA0_RL40_Channel Config_RA.pdf>> ------------- DAY 5 ---------------- DL Transmission UE gets CQI - from SINR - taken from RSRQ - taken from RSRP RSRQ = NumberofResrouceBlock* RSPR/ RSSI PDCCH Adaptation - dynamic size of PDCCH in each frame What is inside PDDCH ? Different types of format format 0 - for UL grant format 1c - for paging and system information format 2 - for downlink resource allocation in MIMO mode format 3 - for TPC command TPC - Transport Prower controll TPC-RNTI How Ue know which aggretation level is allocated to it ? - how much CCE is allocated to me Blind detectetion - I will try to find Ue will do blind detection how many from 8 CCE, if cannot decode 4 CCE, than 2 CCE and 1 CCE (Tayal's way to learn LTE ) nitintayal-lte-tutorialsblogspot.de/2013/05/all-about-pdcch-and-cce-allocation.html CQI is kind of recommendation from the UE to the ENB Resorce allocation of PDSCH Allocation type 0 Allocation type 1 Allocation type 2 - must define starting point and how much resource block are allocated to you (works good in the uplink)a PUCCH Formats Format 1/1a/1b Scheaduling Request + ACK/NACK FOrmat 2/2a/2b CQI + ACK/NACK Scheaduling request have highest priority We are multiplexing several UE on a single Resource Block for PUCCH to save space (use it more effectively) We are using codes for it: Blockwise code 1,2,3 CAZAC code 1,2,3,4,5,6,7,8,9,10,11,12 there is parameter in enb Delta PUCCH shift - 1, 2, 3 - Can configure in the BTS if Delta enb = 1 = we use 12 CAZAC code , multiply 3 Blockwise code means we can multiplex 36 Ue in one resource block if Delta enb = 2 , we use 6 CAZAC code, multiply 3 Blockwise code we can multiplex 18 if Delta enb = 3 , we use 4 CAZAC code, we can multiplex 12 UE <> PUCCH Planning - (depending on the traffic) How much resource block for format 2 and 1 For format 2 - how much for QCI (Max periodicity is 20 ms) - needed 20 RB per 20 TTI if delta PUCCH shift = 2 , i can schedule (but for format 2 we are not using only CAZAC code, and NOT the Blockwise coding) so I can scheadule 6 Ues (12 CAZAC codes div 2 ) ... after calculation = NumberofResourceBLockforQCI = 4( calculated on the board) Format 1 (NumberofRBForScheadlingRequest) .. caluclation of board NumberOfRBForAckNack ... calculcation on board NetAct - license manager